Zero the dial indicator and flip the switch up to do the push test. Record the deflection [1]. Return the switch to neutral and wait for the tool air pressure in the tool to normalize
If the dial does not return to zero, re-zero the indicator before performing the pull test. Flip the switch down and record the deflection [2] for the pull test.
Return the switch to neutral and record the value on the dial indicator. This is the lost motion. Make a note of this value on the Mill Spindle Inspection Checklist.
Pull the dial indicator away and spin the spindle to reset it.
Add the two deflections together. For 40T/HSK machines the tolerance is NTE 0.0025 in (0.0635 mm) and for 50T machines it is NTE 0.003 in (0.0762 mm). Do not include the lost motion in this calculation.